PREDATION II POPULATION CONSEQUENCES
MODELS OF THE MECHANISM OF PREDATION
I. Density dependent effects
A. Note that the Lotka-Volterra model predicts density independent relationships between
predators and prey
B. Are there other factors of the predator-prey relationship that are suitable for mathematical
treatment?
1. Effect of the prey density
2. Effect of the predators
3. Prey characteristics
a) detectability
b) reactions to predators
4. Predator characteristics
a) efficiency
b) food capture and handling methods
c) prey preferences
d) learning
e) hunger state
5. Density and quality of alternate prey
II. Responses of predators to different prey abundances
A. Functional response:
As prey density increases, the per capita predation rate increases up to some level and then stays
constant at some maximum.
B. Numerical response
As prey density increases the number of predators increases
1) by increased reproduction
2) by migration
III. Holling's predator response curves
A. Type I - Per capita consumption of prey is directly proportional to prey density at low prey
numbers and there is a threshold beyond which consumption is constant.
B. Type II - Per capita consumption rises at a continually decreasing rate with increasing prey
density.
C. Type III. - A sigmoid functional response curve i.e. a lag in predator response to prey
density at low prey densities - no search image etc.
D. 'Type IV' - Sigmoid with compensation
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